<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>2-1</title>
		<style>
			div{
				color:red;
				background:yellow;
			}
			.d1{
				color:greenyellow;
				background: red;
			}
			.d2{
				color:yellow;
				background: purple;
			}
			#d3{
				color:pink;
				background: black;
			}
			[ab="d4"]
			{
				color:purple;
				background: yellow;
			}
		</style>
	</head>
	<body>
	<div>1</div>
	<div class="d1">1</div>
	<div class="d1 d2">2</div>
	<div id="d3">3</div>
	<div ab="d4">4</div>
	</body>
</html>
